import {
  Color,
  DepthTexture,
  LinearFilter,
  MathUtils,
  Matrix4,
  Mesh,
  NearestFilter,
  PerspectiveCamera,
  Plane,
  RGBFormat,
  ShaderMaterial,
  UniformsUtils,
  UnsignedShortType,
  Vector2,
  Vector3,
  WebGLRenderTarget
} from '../../three.module.js';

class ReflectorForSSRPass extends Mesh {

  constructor(geometry, options = {}) {

    super(geometry);

    this.type = 'ReflectorForSSRPass';

    const scope = this;

    const color = (options.color !== undefined) ? new Color(options.color) : new Color(0x7F7F7F);
    const textureWidth = options.textureWidth || 512;
    const textureHeight = options.textureHeight || 512;
    const clipBias = options.clipBias || 0;
    const shader = options.shader || ReflectorForSSRPass.ReflectorShader;
    const useDepthTexture = options.useDepthTexture === true;
    const yAxis = new Vector3(0, 1, 0);
    const vecTemp0 = new Vector3();
    const vecTemp1 = new Vector3();

    //

    scope.needsUpdate = false;
    scope.maxDistance = ReflectorForSSRPass.ReflectorShader.uniforms.maxDistance.value;
    scope.opacity = ReflectorForSSRPass.ReflectorShader.uniforms.opacity.value;
    scope.color = color;
    scope.resolution = options.resolution || new Vector2(window.innerWidth, window.innerHeight);


    scope._distanceAttenuation = ReflectorForSSRPass.ReflectorShader.defines.DISTANCE_ATTENUATION;
    Object.defineProperty(scope, 'distanceAttenuation', {
      get() {

        return scope._distanceAttenuation;

      },
      set(val) {

        if (scope._distanceAttenuation === val) return;
        scope._distanceAttenuation = val;
        scope.material.defines.DISTANCE_ATTENUATION = val;
        scope.material.needsUpdate = true;

      }
    });

    scope._fresnel = ReflectorForSSRPass.ReflectorShader.defines.FRESNEL;
    Object.defineProperty(scope, 'fresnel', {
      get() {

        return scope._fresnel;

      },
      set(val) {

        if (scope._fresnel === val) return;
        scope._fresnel = val;
        scope.material.defines.FRESNEL = val;
        scope.material.needsUpdate = true;

      }
    });

    const normal = new Vector3();
    const reflectorWorldPosition = new Vector3();
    const cameraWorldPosition = new Vector3();
    const rotationMatrix = new Matrix4();
    const lookAtPosition = new Vector3(0, 0, -1);

    const view = new Vector3();
    const target = new Vector3();

    const textureMatrix = new Matrix4();
    const virtualCamera = new PerspectiveCamera();

    let depthTexture;

    if (useDepthTexture) {

      depthTexture = new DepthTexture();
      depthTexture.type = UnsignedShortType;
      depthTexture.minFilter = NearestFilter;
      depthTexture.magFilter = NearestFilter;

    }

    const parameters = {
      minFilter: LinearFilter,
      magFilter: LinearFilter,
      format: RGBFormat,
      depthTexture: useDepthTexture ? depthTexture : null,
    };

    const renderTarget = new WebGLRenderTarget(textureWidth, textureHeight, parameters);

    if (!MathUtils.isPowerOfTwo(textureWidth) || !MathUtils.isPowerOfTwo(textureHeight)) {

      renderTarget.texture.generateMipmaps = false;

    }

    const material = new ShaderMaterial({
      transparent: useDepthTexture,
      defines: Object.assign({}, ReflectorForSSRPass.ReflectorShader.defines, {
        useDepthTexture
      }),
      uniforms: UniformsUtils.clone(shader.uniforms),
      fragmentShader: shader.fragmentShader,
      vertexShader: shader.vertexShader
    });

    material.uniforms['tDiffuse'].value = renderTarget.texture;
    material.uniforms['color'].value = scope.color;
    material.uniforms['textureMatrix'].value = textureMatrix;
    if (useDepthTexture) {

      material.uniforms['tDepth'].value = renderTarget.depthTexture;

    }

    this.material = material;

    const globalPlane = new Plane(new Vector3(0, 1, 0), clipBias);
    const globalPlanes = [globalPlane];

    this.doRender = function (renderer, scene, camera) {

      material.uniforms['maxDistance'].value = scope.maxDistance;
      material.uniforms['color'].value = scope.color;
      material.uniforms['opacity'].value = scope.opacity;

      vecTemp0.copy(camera.position).normalize();
      vecTemp1.copy(vecTemp0).reflect(yAxis);
      material.uniforms['fresnelCoe'].value = (vecTemp0.dot(vecTemp1) + 1.) / 2.; // TODO: Also need to use glsl viewPosition and viewNormal per pixel.

      reflectorWorldPosition.setFromMatrixPosition(scope.matrixWorld);
      cameraWorldPosition.setFromMatrixPosition(camera.matrixWorld);

      rotationMatrix.extractRotation(scope.matrixWorld);

      normal.set(0, 0, 1);
      normal.applyMatrix4(rotationMatrix);

      view.subVectors(reflectorWorldPosition, cameraWorldPosition);

      // Avoid rendering when reflector is facing away

      if (view.dot(normal) > 0) return;

      view.reflect(normal).negate();
      view.add(reflectorWorldPosition);

      rotationMatrix.extractRotation(camera.matrixWorld);

      lookAtPosition.set(0, 0, -1);
      lookAtPosition.applyMatrix4(rotationMatrix);
      lookAtPosition.add(cameraWorldPosition);

      target.subVectors(reflectorWorldPosition, lookAtPosition);
      target.reflect(normal).negate();
      target.add(reflectorWorldPosition);

      virtualCamera.position.copy(view);
      virtualCamera.up.set(0, 1, 0);
      virtualCamera.up.applyMatrix4(rotationMatrix);
      virtualCamera.up.reflect(normal);
      virtualCamera.lookAt(target);

      virtualCamera.far = camera.far; // Used in WebGLBackground

      virtualCamera.updateMatrixWorld();
      virtualCamera.projectionMatrix.copy(camera.projectionMatrix);

      material.uniforms['virtualCameraNear'].value = camera.near;
      material.uniforms['virtualCameraFar'].value = camera.far;
      material.uniforms['virtualCameraMatrixWorld'].value = virtualCamera.matrixWorld;
      material.uniforms['virtualCameraProjectionMatrix'].value = camera.projectionMatrix;
      material.uniforms['virtualCameraProjectionMatrixInverse'].value = camera.projectionMatrixInverse;
      material.uniforms['resolution'].value = scope.resolution;

      // Update the texture matrix
      textureMatrix.set(
        0.5, 0.0, 0.0, 0.5,
        0.0, 0.5, 0.0, 0.5,
        0.0, 0.0, 0.5, 0.5,
        0.0, 0.0, 0.0, 1.0
      );
      textureMatrix.multiply(virtualCamera.projectionMatrix);
      textureMatrix.multiply(virtualCamera.matrixWorldInverse);
      textureMatrix.multiply(scope.matrixWorld);

      // Render

      renderTarget.texture.encoding = renderer.outputEncoding;

      // scope.visible = false;

      const currentRenderTarget = renderer.getRenderTarget();

      const currentXrEnabled = renderer.xr.enabled;
      const currentShadowAutoUpdate = renderer.shadowMap.autoUpdate;
      const currentClippingPlanes = renderer.clippingPlanes;

      renderer.xr.enabled = false; // Avoid camera modification
      renderer.shadowMap.autoUpdate = false; // Avoid re-computing shadows
      renderer.clippingPlanes = globalPlanes;

      renderer.setRenderTarget(renderTarget);

      renderer.state.buffers.depth.setMask(true); // make sure the depth buffer is writable so it can be properly cleared, see #18897

      if (renderer.autoClear === false) renderer.clear();
      renderer.render(scene, virtualCamera);

      renderer.xr.enabled = currentXrEnabled;
      renderer.shadowMap.autoUpdate = currentShadowAutoUpdate;
      renderer.clippingPlanes = currentClippingPlanes;

      renderer.setRenderTarget(currentRenderTarget);

      // Restore viewport

      const viewport = camera.viewport;

      if (viewport !== undefined) {

        renderer.state.viewport(viewport);

      }

      // scope.visible = true;

    };

    this.getRenderTarget = function () {

      return renderTarget;

    };

  }

}

ReflectorForSSRPass.prototype.isReflectorForSSRPass = true;

ReflectorForSSRPass.ReflectorShader = {

  defines: {
    DISTANCE_ATTENUATION: true,
    FRESNEL: true,
  },

  uniforms: {

    color: {value: null},
    tDiffuse: {value: null},
    tDepth: {value: null},
    textureMatrix: {value: new Matrix4()},
    maxDistance: {value: 180},
    opacity: {value: 0.5},
    fresnelCoe: {value: null},
    virtualCameraNear: {value: null},
    virtualCameraFar: {value: null},
    virtualCameraProjectionMatrix: {value: new Matrix4()},
    virtualCameraMatrixWorld: {value: new Matrix4()},
    virtualCameraProjectionMatrixInverse: {value: new Matrix4()},
    resolution: {value: new Vector2()},

  },

  vertexShader: /* glsl */`
		uniform mat4 textureMatrix;
		varying vec4 vUv;

		void main() {

			vUv = textureMatrix * vec4( position, 1.0 );

			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,

  fragmentShader: /* glsl */`
		uniform vec3 color;
		uniform sampler2D tDiffuse;
		uniform sampler2D tDepth;
		uniform float maxDistance;
		uniform float opacity;
		uniform float fresnelCoe;
		uniform float virtualCameraNear;
		uniform float virtualCameraFar;
		uniform mat4 virtualCameraProjectionMatrix;
		uniform mat4 virtualCameraProjectionMatrixInverse;
		uniform mat4 virtualCameraMatrixWorld;
		uniform vec2 resolution;
		varying vec4 vUv;
		#include <packing>
		float blendOverlay( float base, float blend ) {
			return( base < 0.5 ? ( 2.0 * base * blend ) : ( 1.0 - 2.0 * ( 1.0 - base ) * ( 1.0 - blend ) ) );
		}
		vec3 blendOverlay( vec3 base, vec3 blend ) {
			return vec3( blendOverlay( base.r, blend.r ), blendOverlay( base.g, blend.g ), blendOverlay( base.b, blend.b ) );
		}
		float getDepth( const in vec2 uv ) {
			return texture2D( tDepth, uv ).x;
		}
		float getViewZ( const in float depth ) {
			return perspectiveDepthToViewZ( depth, virtualCameraNear, virtualCameraFar );
		}
		vec3 getViewPosition( const in vec2 uv, const in float depth/*clip space*/, const in float clipW ) {
			vec4 clipPosition = vec4( ( vec3( uv, depth ) - 0.5 ) * 2.0, 1.0 );//ndc
			clipPosition *= clipW; //clip
			return ( virtualCameraProjectionMatrixInverse * clipPosition ).xyz;//view
		}
		void main() {
			vec4 base = texture2DProj( tDiffuse, vUv );
			#ifdef useDepthTexture
				vec2 uv=(gl_FragCoord.xy-.5)/resolution.xy;
				uv.x=1.-uv.x;
				float depth = texture2DProj( tDepth, vUv ).r;
				float viewZ = getViewZ( depth );
				float clipW = virtualCameraProjectionMatrix[2][3] * viewZ+virtualCameraProjectionMatrix[3][3];
				vec3 viewPosition=getViewPosition( uv, depth, clipW );
				vec3 worldPosition=(virtualCameraMatrixWorld*vec4(viewPosition,1)).xyz;
				if(worldPosition.y>maxDistance) discard;
				float op=opacity;
				#ifdef DISTANCE_ATTENUATION
					float ratio=1.-(worldPosition.y/maxDistance);
					float attenuation=ratio*ratio;
					op=opacity*attenuation;
				#endif
				#ifdef FRESNEL
					op*=fresnelCoe;
				#endif
				gl_FragColor = vec4( blendOverlay( base.rgb, color ), op );
			#else
				gl_FragColor = vec4( blendOverlay( base.rgb, color ), 1.0 );
			#endif
		}
	`,
};

export {ReflectorForSSRPass};
